This invention relates to a chuck unit for a machine tool capable of holding a workpiece at a section which is circular or non-circular.
A conventional chuck unit for a machine tool to be installed on a lathe or the like is usually produced for holding a workpiece having a section that is circular. It may not be possible to hold a workpiece having a section that is a polygon or an irregular shape, except in a chuck with special or customized jaws.
Recently, the machining capabilities of machine tools, such as lathes, have become more complicated and have advanced highly. Various machining operations, such as milling machining, fraise machining, and drilling machining, are possible in addition to mere lathe turning.
For efficient machining, it may be desirable to complete all the machining steps needed on a workpiece in a given machine tool in such a way that a workpiece is subjected to a first routine of machining while held by a first chuck unit, and then is delivered to a second chuck unit facing the first chuck unit. The second chuck unit holds the workpiece by the portion that was machined during the first routine of machining. A second routine of machining is then executed on the portion which has not yet been machined, such as the portion that had been held by the first chuck unit.
In such a case, the portion of the workpiece to be held by the second chuck unit, namely the portion on which the first routine of machining has already been finished, may not always have a circular section. It may have various shapes. In fact, due to increasingly diverse machining operations in recent years, the sectional shape may not be circular in most cases. Nevertheless, it is necessary to execute the second routine of machining while properly holding even such a workpiece.
In a conventional method of using so-called raw jaws, it is possible to machine single use raw jaws for every change of a workpiece. This is not efficient, and the jaws cannot be used to machine various kinds of workpieces. There is a need for a chuck unit capable of properly holding a workpiece having various sectional shapes without troublesome work, such as machining of raw jaws.
German patent No. 19755517 discloses a technique wherein a plurality of workpiece holding rods are provided at a workpiece holding member, such as a jaw. The rods are free to move in a radial direction, and a workpiece having various shapes can be held by such workpiece holding rods. At least two such workpiece holding members need to be provided in a chuck unit to hold the workpiece. The particular structure of the workpiece holding rods and workpiece holding members, and how they are to be driven, and how driving operations of the workpiece holding rod are executed, and the nature of the fixing operation, are problems which remain to be solved.
If the workpiece holding rods and workpiece holding members operate such that every workpiece holding member or workpiece holding rod needs to be moved and driven, then setting and holding the workpiece takes some time. If moving and driving the workpiece holding rod to a predetermined position, and an operation for then fixing the workpiece, are executed with respectively different driving means, it may be necessary to operate driving means at two places concerning each workpiece holding member. The choices are troublesome, and often impractical.
The object of the present invention is to provide a chuck unit for machine tool capable of properly holding a workpiece having various sectional shapes, not limited to a circular section, and capable of executing moving and driving operations and fixing operations using workpiece holding rods, by a simple operation driven from outside the workpiece holding parts, taking the above-mentioned circumstances into consideration.
It is an aspect of the invention that a chuck unit for a machine tool is capable of holding a workpiece, the chuck unit being installed on a spindle that is rotatably supported. The chuck unit comprises a main body that is free to rotate and drive, defining an axial center. Two or more sliding members are provided on said main body. The sliding members are free to move in a radial direction with respect to said axial center of the main body, through sliding member driving means. A workpiece holding member is provided on said each sliding member. The workpiece holding member is capable of moving together with said sliding member. A plurality of workpiece holding rods are provided on the workpiece holding member. The workpiece holding rods are free to move and drive in the radial direction relative to the axial center. The workpiece holding rods are driven by a fluid cylinder driving means. The fluid cylinder driving means has a cylinder formed in each such workpiece holding member. The workpiece holding rod is engaged with said cylinder and is free to move and reciprocate. A member moving mechanism is provided between the sliding member and the workpiece holding member, such that said respective workpiece holding members are free independently to move and drive in the radial direction by operation of the member moving mechanism. The member moving mechanism has an adjustable screw mechanism rotatably provided between said sliding member and said workpiece holding member, such that the workpiece holding member is free to move and drive with respect to said sliding member in said radial direction, by operating the adjustable screw mechanism. The adjustable screw mechanism has a screw operation portion, operable by a rotating jig, rotatably provided at said machine tool, on an outer peripheral side of said chuck unit. A workpiece end face abutting means is provided at said main body. The abutting means is free to move, drive and become fixed in the axial direction relative to the main body. A workpiece end face abutting face is formed at a top end of said workpiece end face abutting means, at a right angle with respect to said axial center direction of the main body.
The workpiece holding rods as described can hold a workpiece at a portion that has been machined or has various sectional shapes, not limited to shapes having a circular section. Machining is possible on the workpiece, even assuming a machined and/or noncircular sectional shape, without the need for raw jaws to hold an irregular or already machined sectional portion. Thus, a first routine of machining and a second routine of machining can be successively executed with a single machine tool, including first holding one portion of the workpiece while machining another, delivering the workpiece between spindles, and then holding the now-machined portion while machining the portion that was previously held. The efficiency of machining work can be rapidly improved.
The workpiece holding members can be respectively independently moved by the member moving mechanism. This makes it readily possible to hold workpieces that have any of a variety of different sectional shapes. The adjustable screw mechanism of the member moving mechanism has a screw operating portion that is rotatable and drivable by the rotating operation jig . Accordingly, the position of the member moving mechanism can be adjusted mechanically rather than by hand, which contributes to automation of the machining operations.
The workpiece holding member can rapidly be moved to a position approaching the workpiece by the member moving mechanism. It is possible to adapt to a new workpiece diameter by moving the workpiece holding rod, and not necessarily by changing the length of its moving stroke. As a result, the workpiece holding member can be compact.
The workpiece also can be held because the workpiece end face is abutted by the workpiece end face abutting face. Workpieces are securely held even if they have irregular shapes.
According to another aspect, the sliding member driving means has first members that are free to move in the axial center direction, and an engagement portion formed at said first members. The sliding member is connected with said engagement portion. The workpiece holding member can be easily driven through the sliding members by driving and reciprocating the first members in the axial center direction.
A plurality of said sliding members can be connected with said engagement portions, and a plurality of said sliding members can be provided that are free synchronously to move through said engagement portions by moving said first members in said axial center direction. All of the workpiece holding members can be synchronously driven by driving the first members in this way.
Furthermore, a piston can be engaged with the cylinder of the workpiece holding means. The piston is free to drive and reciprocate from an outside-in, by a piston operating means. An operating portion is provided at said piston operating means, operable by a rotating operation jig rotatably and drivably provided on the machine tool. The workpiece holding rod can be easily operated from outside the workpiece holding means by operating the piston operating means through the rotating operating jig.
The operating portion can be located on an outer peripheral side of the chuck unit. The operating portion can be operated from the side face of the chuck since it is located on the outer peripheral side of the chuck. Interference between the operating portion and the workpiece during machining can thus be prevented.
In another aspect, the cylinder can have a plurality of sub-cylinders. The workpiece holding rod then is engaged with said each sub-cylinder. The sub-cylinder makes it possible to optionally choose the size of the workpiece holding rod, according to the machining forms and workpiece to be held and machined.
A workpiece core clamping member can be provided at said main body, with an axial center corresponding to the axial center of said main body.
The workpiece can be prevented from shifting from a core when the workpiece is held by the workpiece holding rods with the workpiece core clamping member.
An energizing means is provided for the workpiece holding rods, for energizing said workpiece holding rods from said axial center side in the direction of a retracted position.
The workpiece holding rods can be positively retractable to retreated positions by the energizing means. This prevents interference between the workpiece and the workpiece holding rods when the workpiece holding rods project and otherwise might interfere at the time of a following workpiece holding operation.
The cylinders of said respective workpiece holding members are communicated and connected with each other among the respective workpiece holding members. Thus, the cylinders of all the workpiece holding members can be driven at one time. This makes operation of the workpiece holding rod easier, at the time of delivering of the workpiece, even if a workpiece having a different sectional shape is held every time. The workpiece can be delivered in a short time.
Although the cylinders of said respective workpiece holding members are communicated and connected with each other among the respective workpiece holding members, the piston operation means can be provided at only one of said respective workpiece holding members. The structure of the chuck unit can thus be made simple.
The chuck unit can be installed on a spindle that is rotatably supported. The chuck unit includes a main body that is free to rotate and drive on an axial center as its center. Two or more sliding members provided on said main body are free to move in a radial direction with respect to said axial center of said main body through sliding member driving means. A workpiece holding member is provided on said each sliding member, being free to move together with said sliding member. A plurality of workpiece holding rods provided on said workpiece holding member, are free to move and drive in said radial direction with said axial center as its center through a cylinder. Outside fluid supply means are connected with said cylinder, to supply said cylinder with fluid for driving one or more of the workpiece holding rods from an outside. Fixing means are provided at said workpiece holding rod. Working fluid supply means are connected with said fixing means, for working and releasing working the fixing means. The outside fluid supply means has valve means for changing a supply of said fluid for driving the workpiece holding rod with respect to said cylinder; and said valve means also can serve as said working fluid supply means.
A workpiece can be held by the workpiece holding rods through a portion machined in various sectional shapes that can be non-circular shape. A workpiece with a non-circular sectional shape can be machined without raw jaws, but by holding a machined irregular sectional portion. It is therefore possible to execute a first routine of machining and a second routine of machining successively with a single machine tool, delivering the workpiece between spindles. The efficiency of machining work can be rapidly improved.
The workpiece holding rods can be fixed by the fixing means of the workpiece holding rod, when in the state of holding the workpiece. So, it is not necessary to change the workpiece holding rod positions to follow the outer shape of the workpiece every time when holding a further similar workpiece. The time for delivering workpieces can be shortened and productivity can be improved.
The outside fluid supply means can serve as the valve means for controlling supply of the fluid for driving the workpiece holding rod and the supply means of the working fluid. The chuck unit can be made small. Besides, moving and driving operations and fixing operations on the workpiece holding rods, can be executed by merely operating the outside fluid supply means. So, the operation finishes in a short time and automation with a robot is easy.
The valve means has a driving force receiving portion for receiving a driving force for driving said valve means from outside of the chuck. The driving force receiving portion also serves as a driving force receiving portion for receiving driving force for driving said working fluid supply means from outside of the chuck.
Driving of the valve means and supply of the working fluid also can be executed with the same operating means in the operation from outside, and the operation is simple.
According to another aspect, a chuck unit for a machine tool, capable of holding a workpiece, installed on a spindle rotatably supported, comprises:
a main body that is free to rotate and drive with an axial center as its center;
two or more sliding members provided on said main body, the sliding members being free to move in a radial direction with respect to said axial center of said main body through sliding member driving means;
a workpiece holding member provided on each said sliding member, free to move together with said sliding member;
a plurality of workpiece holding rods provided on said workpiece holding member, the workpiece holding rods being free to move and drive in said radial direction with said axial center as its center through a cylinder;
outside fluid supply means connected with said cylinder, to supply said cylinder with fluid for driving workpiece holding rod from outside of the main body;
fixing means for said workpiece holding rod provided at said workpiece holding rod;
working fluid supply means connected with said fixing means, for working and releasing the fixing means;
said cylinders of said respective workpiece holding members communicating and being connected with one another among said respective workpiece holding members; and
said fixing means of said respective workpiece holding members communicated and connected with each other among said respective workpiece holding members.
A workpiece can be held by the workpiece holding rods as described, at a portion machined in various sectional shapes, including non-circular shapes. The workpiece with such possibly non-circular sectional shape can be machined without the need for raw jaws, namely by holding the machined irregular (potentially non-circular) section. In this way, a first routine of machining and a second routine of machining can be successively executed with a single machine tool, including delivering the workpiece between spindles in the process, and the efficiency of machining work can be rapidly improved.
The workpiece holding rods can be set when holding a workpiece, so as to fix the rods to hold a shape. Thus, it is not necessary to re-set the workpiece holding rods to follow the shape of a workpiece every time a workpiece is held, when a plurality of the workpieces having the same shape are successively machined. The time to complete workpieces can be shortened and productivity improved.
Furthermore, the cylinders and the fixing means of each workpiece holding member are respectively communicated and connected with one another. So, all of the workpiece holding members can be driven by one operative fluid supply means and fixing means associated with one the workpiece holding rod.
The outside fluid supply means have a valve means for controlling supply of said fluid for driving the workpiece holding rod with respect to said cylinder. The valve means also serves as the working fluid supply means.
The outside fluid supply means and said working fluid supply means for working and releasing said fixing means preferably are provided at only one of the workpiece holding members installed on said main body. Therefore, the structure of the chuck unit can be made simple.
The workpiece holding member and said sliding member can be unitedly formed with each other. So, the chuck unit can be made smaller.